AB0850 Enthesitis, female gender and vitality perception as fatigue determinants in spondyloarthritis patients under bDMARD
Authors: F. R. Martins, A. Martins, B. Samões, D. Santos Oliveira, R. Nicolau, F. Oliveira Pinheiro, M. Rato, M. Bernardes, L. Costa
Journal: Annals of the Rheumatic Diseases (2022)

Background Fatigue is an important domain in quality of life of spondyloarthritis patients, not always directly associated with disease course. The explanatory factors of fatigue in these patients are still not clearly understood. Objectives To assess the determinants of fatigue in patients with SpA under biologic disease modifying anti-rheumatic drugs (bDMARDs). Methods A retrospective observational study was performed using registry data of patients with SpA under bDMARD therapy followed at a tertiary level hospital. Data regarding disease activity, response criteria measures, analytic markers, function, metrology, pain, general health and fatigue (using FACIT score) was gathered at baseline, 6 months (t6) and 12 months (t12) after introduction of bDMARD. Statistical analysis (significance at p &lt; 0.05) was performed using paired T-test, Wilcoxon test and McNemar tests for paired samples, Mann Whitney-U, Kruskall-Walis and One Way ANOVA for independent samples. Linear and logistic regression models were performed to assess direction and strength of association. Results A total of 46 SpA patients were analysed; most were male (24, 52.2%) with a predominantly axial involvement (31, 68.9%) and 74.4% of them were positive for HLA-B27. Most patients had high school or lower education (29, 69.1%), never smoked (26, 61.9%), never drank (34, 79.1%) and had a full-time job (38, 88.4%). All patients were under TNF inhibitors, mostly adalimumab (23, 50%). There was a significant decrease in inflammatory markers (p&lt;0.001), disease activity scores (ASDAS-CRP and BASDAI) (p&lt;0.001), function index BASFI (p&lt; 0.001), metrology indexes (p&lt;0.05) and MASES enthesitis score (p&lt; 0.01). Patient, physician and night pain VAS were significantly lower (p&lt; 0.001) at t6 and t12, but spine VAS only varied significantly between t0 - t6 (p = 0.021) and not t0 - t12 (p= 0.405). FACIT didn’t vary significantly after bDMARD initiation, and among the domains of SF36 questionnaire, only SF36 vitality score varied significantly (p&lt;0.05). No significant changes in EQ5D, HADs anxiety or depression scores were observed. At baseline, there was a strong negative correlation between fatigue, expressed by FACIT score, and pain VAS (R = 0.9, p=0.037), without other significant associations. Several positive correlations with fatigue at t6 were observed, the strongest with anxiety and depression HADs (p &lt; 0.001), BASFI (p &lt; 0.001) and ASDAS-CRP (p&lt; 0.001). Other positive associations were seen with 66 TJC (p &lt;0.01), patient VAS (p&lt;0.001, pain VAS (p = 0.001), nocturnal pain VAS (p &lt;0.001), BASDAI (p &lt;0.001) and MASES (p &lt;0.001). Fatigue at t6 had a negative correlation with increased ASAS response measures mean value (p = 0.014), all domains of SF36 (p &lt; 0.001), the strongest correlation of which was with the general health domain (R=-0.811), and EQ5D (p&lt;0.001). When comparing subgroups at t6, there was more fatigue in the female group (p=0.01) and in patient with higher ASDAS disease activity score (p &lt; 0.05), with no differences according to work status, alcohol consumption or tobacco use, educational level, TNF inhibitor exposure or ASAS response. Prediction analysis showed univariable association between several baseline variables and fatigue (lower FACIT scoring) at t6: age at bDMARD introduction (B = - 0,405, p = 0.02), age at diagnosis (B = -0.43, p = 0.02), physician VAS (B = 0.149, p &lt; 0.05), MASES (B = -1.732, p &lt;0.001), SPARCC (p &lt; 0.05) and female gender (B = -7.95, p = 0.01). Multivariate linear regression analysis allowed for creation of a predictive model for FACIT scoring at t6 (R2 = 0.900, p = 0.019): (-3.426) x MASES t0 + (-24.074) x female gender + 0.949 x SF36 vitality score. Conclusion Enthesitis, female gender and subjective assessment of vitality seem to be determinants of fatigue in SpA patients under bDMARD. Fatigue in this population is associated with diverse factors that should be optimized in a holistic approach to the patient. Disclosure of Interests None declared